Hybrid axle assembly for a motor vehicle

ABSTRACT

An axle assembly for an electric or hybrid vehicle includes electrically powered drive motors for respectively driving vehicle wheels. The axle assembly preferably includes a dual motor arrangement, wherein two electric motors are arranged end-to-end. Each motor includes an inverter that is directly connected to its respective motor, and includes a gearbox assembly coupled between an output of the motor and a corresponding constant-velocity (CV) joint operatively connected to a wheel. The inboard ends of the motors are secured to opposite faces of a cooling manifold wherein the cooling manifold maintains the motors in axial alignment. The cooling manifold plate is positioned between an inboard end of each of the motor housings, and the cooling manifold plate axially aligns the first and second motors. Further, each motor drives its respective gearbox assembly, which includes a gear reduction and clutch mechanism having a brake band assembly that is selectively operable to disconnect the respective motor from the vehicle wheel associated therewith.

CROSS REFERENCE TO RELATED APPLICATIONS

This application asserts priority from provisional application61/793,593, filed on Mar. 15, 2013, which is incorporated herein byreference.

FIELD OF THE INVENTION

The invention relates to an axle assembly for a motor vehicle and moreparticularly, to an axle assembly for a hybrid vehicle having a dualmotor drive unit for driving the vehicle wheels.

BACKGROUND OF THE INVENTION

It is known to provide an electric or hybrid vehicle with an axleassembly using electric motors to drive selected wheels on the vehicle.

The invention relates to an improved axle assembly for an electric orhybrid vehicle, which includes electrically powered drive motors forrespectively driving one or more vehicle wheels. The axle assemblypreferably includes a dual motor arrangement, wherein two electricmotors are arranged end-to-end. Each motor includes an inverter that isdirectly connected to its respective motor. The inverters preferably aremounted on opposite sides of the axle assembly and convert DC power fromthe vehicle's battery and power generation system to AC power to drivethe motors. In addition, each motor includes a gearbox assembly coupledbetween an output of the motor and a corresponding support mechanism,such as a constant-velocity (CV) joint, operatively connected to awheel. Each gearbox assembly selectively transfers torque or rotationalmovement from an output shaft of the motor to the wheel.

In one aspect of the invention, the electric axle assembly of theinvention includes a pair of the electric motors, which are arrangedback-to-back with a single cooling manifold located between inboardadjacent ends of the motors. The inboard ends of the motors are securedto opposite faces of the cooling manifold wherein an axis of rotation ofeach motor output shaft is aligned in registry with the axis of theother motor so that the cooling manifold maintains said motors in axialalignment.

The motors are disposed within separate, respective motor housings andthe cooling manifold seals an inboard end of each housing. Each motorincludes one of the power inverters, which is electrically connectedthereto. The power inverters are disposed on opposite forward andrearward sides of the electric axle assembly. Liquid coolant is suppliedto the motors and inverters to cool the motors and associated powerinverters during driving of the vehicle.

More specifically, the coolant flows from the vehicle heat exchangeralong various flow passageways, which preferably are defined byappropriate tubing, piping or the like. The passageways split a flow oflower temperature or cooled coolant, which is fed separately througheach motor in parallel. More particularly, the coolant enters thecooling manifold through a single inlet wherein an internal inletcooling channel provided within the cooling manifold directs the coolantinto multiple inlet ports in the inboard end of each motor to therebyabsorb heat from the motors and cool same. After cooling the motors, theheated coolant is discharged from the inboard end of each motor throughoutlet ports back into an internal outlet cooling channel in the coolingmanifold where the coolant is again merged into a single flow. Theheated coolant exits the cooling manifold at a single location and isthen fed to a first inverter to cool same and then serially into thesecond inverter for cooling. After the second inverter, the coolantreturns to the heat exchanger for subsequent cooling and refeeding ofthe cooled coolant back to the cooling manifold, motors and inverters.The cooling manifold therefore performs the additional function ofdefining flow paths or passageways to allow cooling of the motors.

In another aspect of the invention, the electric axle assembly providesa modular construction, which readily allows for assembly of a dualmotor configuration while also allowing for a modified single motorconfiguration, or the provision of alternate configurations of a gearboxassembly. The axle assembly includes a first electric motor housedwithin a first motor housing and a second electric motor housed within asecond motor housing. More specifically, each motor housing includes acylindrical chamber in which the motor is inserted separately andindependently of the other motor. Preferably, the cooling manifold isformed as a cooling manifold plate formed in a uniformly thick, plateshape. Once one or more motors are installed, the cooling manifold plateis positioned between the inboard end of each of the first and secondmotor housings. As referenced above, the cooling manifold plate axiallyaligns the first and second motors and encloses the first and secondmotors in the respective cylindrical chambers of the respective motorhousings. The first motor is mounted or fixedly secured to a first sideof the cooling manifold plate and the second motor is mounted or fixedlysecured to a second side of the cooling manifold plate. As describedabove, the cooling manifold plate delivers coolant to the first andsecond motors to cool the motors.

Still further, in another aspect of the invention, each motor drives itsrespective gearbox assembly, wherein a first gear-set housing is fixedlysecured to an outboard end of the first motor housing and houses a gearreduction and clutch mechanism that is coupled between the first motorand an output hub that in turn is operatively coupled to a first vehiclewheel. The gear reduction and clutch mechanism reduces a rotationalspeed output by the first motor and increases an output torque. Theinventive gear reduction and clutch mechanism includes a brake bandassembly that is selectively operable to disconnect the first motor fromthe first vehicle wheel.

Similarly, in the dual motor configuration, a second gear-set housing isfixedly secured to an outboard end of the second motor housing andhouses a gear reduction and clutch mechanism that is coupled between thesecond motor and a second output hub that in turn is operatively coupledto a second vehicle wheel. The gear reduction and clutch mechanismreduces a rotational speed output by the second motor and increases anoutput torque. Here again, the gear reduction and clutch mechanismincludes a brake band assembly that is selectively operable todisconnect the second motor from the second vehicle wheel.

More particularly, each gear reduction and clutch mechanism is coupledbetween the outboard end of each electric motor and its respectivevehicle wheel. The gear reduction mechanism includes a planetary gearsystem to provide speed and torque conversion between the electric motorand the vehicle wheel. Preferably, the planetary gear system includes aprimary ring gear having an integrated brake drum or outer surface,which is part of a band brake assembly. The planetary gear systempreferably is a double planetary gear system having two gear sets withone of the gear sets having the primary ring gear cooperating with theband brake assembly. Alternatively, the planetary gear system could haveonly one gear set, or two or more gear sets. The band brake assemblyalso includes a band brake, which engages and releases the outer surfaceof the ring gear for the purpose of connecting and disconnecting theelectric motor with the vehicle wheel. For example, when the band brakeis engaged with the outer surface of the ring gear, the output of theelectric motor is transmitted through the gear reduction mechanism todrive the vehicle wheel. On the other hand, when the band brake isreleased from the outer surface of the ring gear, the output of theelectric motor is not transmitted through the gear reduction mechanism.In other words, when the band brake is released from the outer surfaceof the ring gear, the electric motor is disconnected from the vehiclewheel.

Each motor housing also includes a secondary chamber on front and backsides of the cylindrical chamber for additional components. For example,a first power inverter is directly connected to the first motor and ispositioned in the secondary chamber of the first and second motorhousings. A first cover plate is affixed to the first and second motorhousings to enclose the first power inverter within the secondarychambers. Similarly, a second power inverter is directly connected tothe second motor and is positioned in the secondary chamber of the firstand second motor housings. A second cover plate is affixed to the firstand second motor housings to enclose the second power inverter withinthe secondary chambers.

The gearbox assembly of the invention further also may be formed as atwo-speed transmission unit which is connectable to and driven by themotors. In a first embodiment, a clutch may be provided in combinationwith a clutch to

Other objects and purposes of the invention, and variations thereof,will be apparent upon reading the following specification and inspectingthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric front view of an axle assembly of the inventionas viewed from above.

FIG. 2 is an isometric front view thereof as viewed from below.

FIG. 3 is an isometric rear view thereof.

FIG. 4 is a plan view of the axle assembly.

FIG. 5 is a front view thereof.

FIG. 6 is an end view thereof.

FIG. 7 is an exploded isometric view of the motor drive assembly.

FIG. 8 is an enlarged isometric view thereof.

FIG. 9 is another enlarged isometric view thereof.

FIG. 10A is an enlarged exploded view showing a cooling manifold in adual motor configuration.

FIG. 10B is an enlarged end view of the cooling manifold.

FIG. 10C is a bottom view of the axle assembly.

FIG. 10D is an end view of the first motor.

FIG. 10E is an end view of the second motor.

FIG. 11 is an exploded isometric view of a gearbox assembly showing theoutboard end components.

FIG. 12 is an exploded isometric view of a gearbox assembly showing theinboard end components.

FIG. 13 is a front cross-sectional view of the axle assembly.

FIG. 14 is an enlarged cross-sectional front view of the center axleregion.

FIG. 15 is an enlarged cross-sectional front view of the gearboxassembly and respective motor.

FIG. 16 is an enlarged cross-sectional front view of the gearboxassembly.

FIG. 17 is an enlarged cross-sectional view of a band brake actuator fora band brake assembly.

FIG. 18 diagrammatically shows the cooling system for the axlecomponents.

FIG. 19 is a cross-sectional view showing a first embodiment of atwo-speed transmission unit for mounting to the motor drive assembly ina first operative condition.

FIG. 20 is a cross-sectional view showing a second operative conditionfor the transmission unit.

FIG. 21 is a cross-sectional view showing a second embodiment of atwo-speed transmission unit for mounting to the motor drive assembly ina first operative condition.

FIG. 22 is a cross-sectional view showing a second operative conditionfor the transmission unit.

FIG. 23 diagrammatically illustrates component connections within thesecond transmission unit.

FIG. 24 diagrammatically illustrates component connections within athird transmission unit.

Certain terminology will be used in the following description forconvenience and reference only, and will not be limiting. For example,the words “upwardly”, “downwardly”, “rightwardly” and “leftwardly” willrefer to directions in the drawings to which reference is made. Thewords “inwardly” and “outwardly” will refer to directions toward andaway from, respectively, the geometric center of the arrangement anddesignated parts thereof. Said terminology will include the wordsspecifically mentioned, derivatives thereof, and words of similarimport.

DETAILED DESCRIPTION

Referring to FIGS. 1-3, the invention relates to an improved axleassembly 10 for an electric or hybrid vehicle, which includeselectrically powered drive motors 11 and 12 (FIG. 7) that are enclosedwithin a housing 14 and drive respective gearbox assemblies 15 and 16.The axle assembly 10 includes various improvements over prior art drivesystems.

More particularly, the axle assembly 10 preferably includes a dual motorarrangement, wherein the two electric motors 11 and 12 are arrangedend-to-end for respectively driving vehicle wheel assemblies 17 and 18,which are diagrammatically shown in FIG. 4 in phantom outline. Inaddition, each motor 11 and 12 includes the respective gearbox assembly15 and 16 coupled to a motor output shaft 22 and 23 (FIG. 13) and acorresponding wheel joint provided as part of the wheel assemblies 17and 18 of FIG. 4. Each gearbox assembly 15 and 16 selectively transferstorque or rotational movement to a companion flange or output hub 25 and26, which connects or bolts to the respective wheel assembly 17 and 18.While the axle assembly 10 effects driving of the wheels of therespective wheel assemblies 17 and 18, each gearbox assembly 15 and 16is configured for operatively disconnecting the motor output shaft 22and 23 (FIG. 13) from the companion flange 25 and 26 and associatedwheel assembly 17 and 18 as will be described hereinafter.

Generally, to operate the motors 11 and 12, each motor 11 and 12includes a respective inverter 27 and 28 as seen in FIG. 7 that isdirectly connected to its respective motor 11 and 12. The inverters 27and 28 are provided as part of the vehicle's battery and powergeneration system and preferably are mounted on opposite sides of theaxle assembly 10 to convert DC power supplied from the vehicles batteryand power generation system to AC power to drive the motors 11 and 12.

Referring to FIGS. 1-3, the axle assembly 10 includes the housing 14 towhich the gearbox assemblies 15 and 16 are bolted. The housing 14 isformed as an assembly comprising first and second motor housings 31 and32 and an intermediate cooling manifold 33 which is sandwiched betweenthe motor housings 31 and 32 as will be described further herein. Thisassembly of the motor housings 31 and 32 defines multiple interiorcompartments, which compartments in turn are closed off by front andrear housing panels 33 and 34 and a bottom panel 35. Generally, a bottomcompartment is closed off by the bottom panel 35 wherein the bottomcompartment of the main housing 14 includes a plurality of connectorsfor the connection of various support equipment. As seen in FIG. 3, thebottom compartment wall includes first and second coolant connectors 36and 37 for respectively supplying liquid coolant to and from the axleassembly 10. Further, a power connector 38 is provided to supply DCpower to the inverters 27 and 28 for driving the motors 11 and 12, and acontrol connector 39 is also provided which connects to the vehicle'scontrol system for selectively controlling operation of the axleassembly 10.

More particularly as to the electric axle assembly 10 as seen in FIGS.4-7, a pair of the electric motors 11 and 12 are arranged back-to-backwith the single cooling manifold 33 located between inboard adjacentends of the motors 11 and 12. As will be described further herein, theinboard ends of the motors 11 and 12 are secured to opposite faces 41and 42 of the cooling manifold 33 and an axis of rotation 43 of eachmotor output shaft is aligned in registry with the axis 43 of the otherone of the motors 11 and 12. As such, the cooling manifold 33 maintainssaid motors 11 and 12 in axial alignment.

The motors 11 and 12 are disposed within their separate, respectivemotor housings 31 and 32 and the cooling manifold 33 seals the inboardend of each motor housing 31 and 32. The motor housings 31 and 32 areformed the same as each other so as to have top and bottom walls 44 and45 and interior side walls 46 which are spaced inwardly of the front andrear terminal edges of the top and bottom walls 44 and 45. With thiswall configuration, a motor compartment 47 is formed which openssidewardly along the motor axis 43, while additional side compartments48 are formed externally of the motor compartment 47.

During assembly, each of the motors 11 and 12 is slid axially into itsrespective motor compartment 47 wherein FIGS. 8 and 13 show the motors11 and 12 fully installed and fastened in place within the compartments47. Generally, during assembly, the cooling manifold 33 is sandwichedbetween the motor housings 31 and 32 and between the motor face plates49 and 50 on the inboard ends of the motors 11 and 12. The motors 11 and12 are held in position within the motor housings 31 and 32 bycomplementary slide formations 51 and 52 (FIG. 9). Each motor 11 and 12has one of the power inverters 27 and 28 electrically connected thereto,wherein the power inverters 27 and 28 are disposed within the oppositeforward and rearward side compartments 48 as best seen in FIG. 8. Theside compartments 48 are eventually closed off by the front and rearhousing panels 33 and 34 as shown in FIGS. 1-3.

To bolt the motor housings 31 and 32 and the cooling manifold 33together, the motor housings 31 and 32 are each formed with bolt flanges54 at each top and bottom corner of the side walls 46 as best seen inFIGS. 9 and 10. Each of the bolt flanges 54 has a pair of bores 55,which allows bolts 56 to pass axially therethrough for securing themotor housings 31 and 32 together. The cooling manifold 33 also has fourcorresponding corner flanges 57 with pairs of bores 58 that allow thebolts 56 to pass therethrough and maintains the housings 31 and 32 andmanifold 33 in secure, axial engagement after the bolts are tightened.

Therefore by this assembly, the inventive electric axle assembly 10provides a modular construction which readily allows for assembly of adual motor configuration as shown while also allowing for a modifiedsingle motor configuration wherein one of the motors 11 and 12 may beomitted from its respective housing 31 or 32 while the housings 31 and32 and cooling manifold 33 are still assembled in the same manner asdescribed above. In addition, this axle assembly 10 allows for theprovision of alternate configurations of a gearbox assembly 15 and 16since these mechanisms can be interchanged depending upon the vehiclerequirements.

During assembly, the first electric motor 11 is installed within thefirst motor housing 31 and the second electric motor 12 is installedwithin the second motor housing 32. Each motor 11 and 12 is insertedseparately and independently of the other motor and the motor/housingassembly is then positioned for assembly with the manifold 33.Preferably, the cooling manifold 33 is formed as a cooling manifoldplate formed in a uniformly thick, plate shape. Once one or more motors11 and 12 are installed, the cooling manifold plate 33 is positionedbetween an inboard end of each of the first and second motor housings 31and 32 and these components are bolted together by fastening bolts 56.

As referenced above, the cooling manifold plate 33 axially aligns thefirst and second motors 11 and 12 and covers the first and second motors11 and 12 in the respective cylindrical chambers 47 of the respectivemotor housings 31 and 32. The first motor 11 is mounted or fixedlysecured to a first side 41 of the cooling manifold plate 33 and thesecond motor 12 is mounted or fixedly secured to a second side 42 of thecooling manifold plate 33. Preferably, the opposite sides 41 and 42 ofthe cooling manifold 33 and the motor end plates 50 are provided withcomplementary alignment formations 61 and 62, which preferably areconfigured as male and female recesses and projections that maintainradial alignment of the shaft axis 43 of each motor 11 and 12. In FIG.10A, formation 61 is an axially projecting hub which fits snugly withina complementary socket 62 formed in the motor plate 50. FIG. 14 shows areversed configuration wherein the formation 61 on the manifold 33 isthe socket and the formation 62 on the motor plate 50 is a projectinghub.

As described above, the cooling manifold plate 33 delivers coolant tovarious power electronics including the inverters 27 and 28 and also tothe motors 11 and 12. More specifically, the coolant flows from thevehicle heat exchanger 64 (FIG. 18) along various flow passageways,which preferably are defined by appropriate tubing, piping or the like.The passageways split a flow of lower temperature or cooled coolant asseen in FIG. 18, which flows separately through each power inverter 27and 28 in parallel.

Before cooling the power inverters 27 and 28 and any other desirablepower electronics, the coolant for each power inverter 27 and 28 entersthe cooling manifold 33 (FIG. 10A) which includes arcuate, concentricinternal cooling channels 66 and 68 which open through each of theopposite plate faces 41 and 42 for fluid communication with each of themotors 11 and 12. While the power electronics are cooled downstream ofthe cooling manifold 33, it will be understood that the inverters 27 and28 and other electronics might be cooled upstream of the coolingmanifold 33. The cooling channel 68 serves as an inlet channel, whichreceives cooled fluid through a single inlet port 68A shown in FIGS. 10Band 10C. The inlet port 68A is formed by a bore extending radially fromthe manifold edge which opens into a radial leg 68B formed on one end ofthe channel 68. The cooling channel 68 extends circumferentially andincludes additional radial legs 68C, which facilitate coolant flow intothe motors 11 and 12.

The cooling channel 66 is formed similarly and serves as the outletchannel for collecting heated coolant from the motors 11 and 12 anddischarging same from the cooling manifold 33. The cooling channel 66has a discharge port 66A which opens out of a radial leg 66B at one endof the cooling channel 66. These ports 66A and 68A are connected to theconnectors 37 and 36 by suitable coolant piping or hoses. As such, thecooling manifold 33 has a single point of entry 68A and exit 66A. Thecooling channel 66 also extends circumferentially and includesadditional radial legs 66C, which facilitate coolant flow out of themotors 11 and 12.

Referring to FIGS. 10A, 10D and 10E, each of the cooling channels 66 and68 communicates with a respective group of three coolant ports 71 or 72so that coolant can flow through the channels 66 and 68 and the motors11 and 12. The inlet channel 68 communicates with coolant ports 72wherein the ports 72 align with and open into the radial legs 68B and68C for receiving cooled fluid into the motors 11 and 12. The motors 11and 12 can include coolant piping or tubing which draws heat away fromthe motors 11 and 12 as the coolant flows therethrough. The other ports71 open into the radial legs 66B and 66C of the outlet channel 66, whichreceives the hotter fluid from the motors 11 and 12. Each of the motorplates 50 for the motors 11 and 12 is provided with the same pattern ofports 71 and 72 wherein one of the motor plates 50 is shown in FIG. 10A.The pattern of cooling channels 66 and 68 opens through each of theopposite manifold sides 41 and 42 to respectively direct flow to themotors 11 and 12. Also, the manifold faces 41 and 42 have shallow gasketgrooves disposed radially between the grooves 66 and 68 and radiallyoutside of the outermost groove 66 wherein the gasket grooves includegaskets therein to seal the coolant grooves 66 and 68 radially from eachother which prevents coolant from leaking outside of the coolantmanifold 33.

In operation, the internal cooling channel 68 is fed with the coolant toport 68A and directs the coolant into the inboard end of each motor 11and 12 to thereby absorb heat from the motors 11 and 12 and cool same.After cooling the motors, the heated coolant is discharged from theinboard end of each motor 11 and 12 back into the cooling channel 66where the coolant is merged into a single flow and exits through outletport 66A. The heated coolant exits the cooling manifold 33 at a singlelocation and then is fed to one of the inverters 27 and 28 andthereafter, to the other of the inverters 27 and 28. After exiting thelast inverter, the coolant returns to the heat exchanger 64 forsubsequent cooling and refeeding of the cooled coolant back to themotors 11 and 12, cooling manifold 33 and inverters 27 and 28 asdiagrammatically shown in FIG. 18. The cooling manifold 33 thereforeperforms the additional function of defining flow paths or passagewaysto allow cooling of the motors 11 and 12.

Next, in another aspect of the invention, each motor 11 and 12 drivesits respective gearbox assembly 15 and 16. Since each gearbox assembly15 and 16 is formed substantially the same, common reference numeralsare used for common components thereof. In this regard, FIGS. 1-6generally shows a first gear-set housing 91 fixedly secured to anoutboard end of the first motor housing 31. As described further herein,the gear-set housing 91 houses a gear reduction and clutch mechanismthat is coupled between the first motor 11 and the output hub 25 that inturn is operatively coupled to a first vehicle wheel. The gear reductionand clutch mechanism reduces a rotational speed output by the firstmotor 11 and increases an output torque. Generally, the inventive gearreduction and clutch mechanism includes a band brake assembly 94 that isselectively operable to disconnect the first motor 11 from the firstvehicle wheel 17A (FIG. 18).

Similarly, in the dual motor configuration, a second gear-set housing 91is fixedly secured to an outboard end of the second motor housing 32 andhouses a respective gear reduction and clutch mechanism that is coupledbetween the second motor 12 and a second output hub 26 that in turn isoperatively coupled to a second vehicle wheel 18A (FIG. 18). Here again,the gear reduction and clutch mechanism reduces a rotational speedoutput by the second motor 12 and increases an output torque.

More particularly as to FIGS. 11, 12 and 16, the gear reduction andclutch mechanism is identified by numeral 92 and is assembled within thehousing 91 and coupled between the outboard end of each electric motor11/12 and its respective vehicle wheel assembly 17 or 18. The variousparts of the mechanism 92 are shown in detail in the exploded view inFIGS. 11 and 12, although the following discussion focuses on thesignificant parts that are relevant to an understanding of the presentinvention.

The gear reduction mechanism 92 includes a planetary gear system whichis preferably formed as a double planetary gear system to provide speedand torque conversion between the electric motors 11/12 and the vehiclewheel assemblies 17/18. Most significantly, each planetary gear systemincludes a band brake assembly 94 and a primary ring gear 95 having anintegrated brake drum or outer surface 96, which is part of the bandbrake assembly 94. The band brake assembly 94 also includes a band brake97 and brake actuator 98 (FIGS. 16 and 17), which engages and releasesthe outer surface 96 of the ring gear 95 for the purpose of connectingand disconnecting the electric motor 11/12 with the respective vehiclewheel 17A/18A. Generally, for example, when the band brake 97 is engagedwith the outer surface 96 of the ring gear 95, the output of theelectric motor 11/12 is transmitted through the gear reduction mechanismto drive the vehicle wheel assembly 17/18. On the other hand, when theband brake 97 is released from the outer surface 96 of the ring gear 95,the output of the electric motor 11/12 is not transmitted through thegear reduction mechanism.

More particularly, the double planetary gear set includes a firstinboard gear set 100 having a sun gear 101 driven by the correspondingmotor shaft 22/23, which sun gear 101 in turn drives the planetarypinion gears 102 that drive the planetary carrier 103/104. The piniongears 102 engage the ring gear 95, which is able to rotate relative tothe housing 91 when the band brake 96 is disengaged. The outboardcarrier half 104 drives the sun gear 106 of the outboard gear set 107which in turn drives the planetary pinion gears 108 and planetarycarrier 109/110. The pinion gears 108 engage the outer ring gear 111,which is held stationary relative to the housing 91. An annular bearing112 is provided to allow relative rotation of the ring gear 95 when thering gear 95 is not engaged by the band brake 97. However, the outboardsun gear 106 drives the output hub 25/26 when the primary ring gear 95is held via the brake band 97.

The brake actuator 98 uses a hydraulically operated piston 115 (FIG. 17)to actuate the band brake 97 in two states, clamped and unclamped whichprevents and permits rotation of the ring gear 95. The effect is tocreate an on/off function by changing the state of the inboard planetarygear set 100. The hydraulic piston 115 receives pressurized oil from ahydraulic pump integrated into the electrified axle housing 14, which isa low pressure pump having control/monitoring wiring connected to thevehicle control system and piping to and from the brake band piston 115for selectively operating the piston 115 and engaging and disengagingthe brake band 97.

While a double planetary gear system is preferred, the planetary gearsystem might be formed in a single gear set configuration with only asingle gear set engaged by the band brake 97, or a plural gear setconfiguration having one gear set engaged by the band brake 97 incombination with one or more additional gear sets.

The band brake assembly 94 provides various advantages. There is muchless calibration of the controlling computer required to reachsatisfactory operation. Other types of disconnecting methods like dogclutches, synchro gears and multi-plate clutches requirecharacterization and development to operate correctly across a broadrange of temperatures. Further, the layout of the planetary gearmechanism and the band brake 97 has the ability to be configured in aminimal amount of functional space.

The present invention also provides additional advantages. For example,the modular design provides the advantage wherein the entire unit can beadapted to many vehicles by modifying only the motor housings 31 and 32to fit the available space. The coolant, electrical and controls can useindustry standard interfaces. Further, the configuration of the motorhousings 31 and 32 and the intermediate coolant manifold 33 minimizesthe overall axial length of the axle assembly 10, which creates animproved ability to fit in the space between the left and rightsuspension units of the wheel assemblies 17 and 18. Combining ratioreduction and disconnecting functions of the gear reduction and clutchmechanism in one unit frees the space available outside of the opposedmotors 11 and 21. In turn, this configuration provides the freedom tochange the diameter and length of the opposed electric motors 11 and 12in larger and smaller combinations to fit a multitude of vehicle sizesand propulsion torque requirements. As such, the electric driving motorlength and diameter can be changed without redesign of the band brakeassembly 94.

The axle assembly 10 also provides the advantage of using the coolingmanifold 33 as a combination manifold and motor mount. This providesaxial compactness of the total unit. Further, the power inverters 27 and28 are contained inside the environmentally sealed motor housing 14. Thehousing layout separates the two compartments housing the inverters 27and 28 enabling the easier direct connection to the electric motor andminimization of the overall ‘outside diameter’ of the motor housings 31and 32. Still further, modular motor and clutch units can be mixed andmatched to meet a wide variety of application situations.

Still further as to the axle assembly 10, the metal manifold plate 33has multiple internal passages that can channel cooling fluid in and outof the electric motors 11 and 12. The cooling manifold 33 allows acommon single location to bring to and return cooling fluids from bothmotors 11/12 and both inverters 27/28 simultaneously. The manifold plate33 has been designed in a way that allows the two motors 11/12 to bealigned such that they reside on the same axis 43 and are separated by aminimum possible axial distance so that the total distance between theopposed left-hand and right-hand output hubs 25/26 of the motors 11/12can be confined to the distance between the corresponding left-hand andright hand suspension apparatus in a motor vehicle. The manifold plate33 also provides the function of sealing off the inboard ends of theleft-hand and right-hand housings 31 and 32 that contain the opposedelectric motors 11/12.

Next, referring to FIGS. 19-20, a gear reduction mechanism can be formedas a multi-speed transmission, which includes a planetary gear system toprovide speed and torque conversion between the electric motors 11/12and the vehicle wheel assemblies 17/18. FIGS. 19-20 illustrate a gearreduction mechanism 199, which can be installed in place of the gearreduction mechanism 92 described above. The gear reduction mechanism 199is provided as a double planetary gear set having a first inboard gearset 200 having a sun gear 201 driven by the corresponding motor shaft22/23, which sun gear 201 in turn drives planetary pinion gears 202 thatdrive a planetary carrier 203. The pinion gears 202 engage a ring gear204, which is able to rotate relative to the housing 91 when a bandbrake assembly 94 is disengaged (FIG. 20), or is restrained by the bandbrake 96 (FIG. 19). The carrier 203 drives a sun gear 206 of an outboardgear set 207 which in turn drives planetary pinion gears 208 andplanetary carrier 209 which in turn drive the hub 26. The pinion gears208 engage a stationary or grounded outer ring gear 211. An annularbearing 212 is provided to allow relative rotation of the ring gear 204when the ring gear 204 is not engaged by the band brake assembly 94.

Like the gear reduction mechanism 92, the band brake assembly 94includes a band brake 97 and brake actuator 98 (FIGS. 19 and 20), whichengages and releases the first ring gear 204.

Additionally, a clutch 215 is provided such that when the band brakeassembly 94 is released, the first sun gear 201 and the first carrier203 still rotate to drive the second sun gear 201. More particularly,the clutch 215 can be engaged so that the first carrier 203 and sun gear201 directly drive the second gear set 207, and can be disengaged whenthe band brake assembly 94 is engaged so that the first gear set 200then drives the second gear set 207 as a double planetary gear assembly.

More particularly, when the band brake assembly 94 is engaged as seen inFIG. 19, the first outer ring gear 203 is grounded and stationary. Theclutch 215 is deactivated. The pinion gears 202 walk around the sun gear201 to drive the carrier 202 and in turn drive the second sun gear 206.Since ring gear 211 is grounded, the gears 208 walk around sun gear 206to drive the carrier 209 and the hub 26 connected thereto. Thisoperative condition defines a first speed reduction and output torque.

When the band brake assembly 94 is released as seen in FIG. 20, thefirst outer ring gear 203 is no longer grounded and instead ring gear203 spins freely. However, the clutch 215 is then engaged so that thecarrier 202 rotates to directly drive the second sun gear 206. Thisoperative condition defines a second speed reduction and output torque,which differs from the first so that a two-speed transmission is formed.

In this manner, the first gear set 207 can be shifted to a direct modeto protect motor over speed concerns. The gear set 207 can be changed todirect by the clutch 215 between the two members of gear set 207.Shifting the gear set 207 to direct reduces the speed at the motor by50% and creates a second speed. The clutch 215 can either be hydraulicor mechanical. Hydraulic clutches require seals, pistons, and seal ringsetc. These components all need axial space to be functional. Mechanicalclutches are generally direction sensitive but require less axial spacethan seal rings and clutch plates and pistons. By using a selectablemechanical clutch 215, the transmission can dictate when the clutch 215will be active. The selectable clutch 215 has a device to activate ordeactivate the clutch. Generally, a ball ramp can be used to deactivatethe free wheeler in the clutch 215.

Referring to FIGS. 21-23, a further arrangement is shown. This secondconfiguration 300 uses three plans of gears or gear sets 301, 302 and303, and two input clutches 304 and 305 located before the first gearset 301. The power from the motor is directed through the input shaft22/23 to either of the clutches 304 and 305 depending on the speed andtorque requested by a power train control unit. The gear sets 301-303include respective sun gears S301, S302, S303, pinion gear drivencarriers C301, C302, C303, and ring gears R301, R302, R303. The firstand second sun gears S301 and S302 are driven together by shaft 22/23.

If lower speed and more torque are requested then the first clutch 304would be activated as seen in FIG. 21. The torque from the clutch 304 isdelivered to sun S3011 and sun S302 since both are directly connected toeach other. The torque from sun S302 is transmitted to the gear trainplane and carrier C302. The torque from rotation of the planetary gearsabout sun S302 is split between ring R302 and the carrier C302. RingR302 is connected to carrier C303 which is in turn the output of thetransmission that drives the hub 26. Second carrier C302 is directlyconnected to third sun S303. At this stage in this transmission there isan input and an output and then there is a reaction to ground by ringR303 which is directly connected to ground at the enclosure or case 307of the transmission.

If a higher speed and lower torque are requested, the second clutch 305is activated while first clutch 304 is deactivated. With clutch 305activated, torque is delivered to the first carrier C301. The torque isnow split between the first sun S301 and first ring R301 in relation tothe ring to sun ratio. As described previously first sun S301 and secondsun S302 are connected. Ring S301 is directly connected to secondcarrier C302. The torque flow is the same as previously described exceptfor the lower torque as seen by the bolded torque transmission lines inFIG. 22.

The design of the two clutches 304 and 305 can be hydraulic, mechanicalwith hydraulic release/activating or mechanical with electric release.The second arrangement is shown with hydraulic activated clutches. Thisarrangement thereby provides a two-speed transmission.

There is a third three speed configuration that is shown in FIG. 24 andrepresents a modification of the configuration and components of FIGS.21-23 above. This third arrangement works the same as the secondarrangement through low range and high range which are operated by theclutches 304 and 305 with the third ring R303 being grounded. However, aclutch 306 such as a free wheeler clutch or a plate clutch is added toreplace the permanent attachment of ring R303 to the transmission case307 (ground). As such, it is possible to create a direct mode meaningthe transmission ratio will become 1:1 or equal to motor RPM. To achievethis state both input clutches 304 and 305 would be activated. Theapplication of both clutches will cause all of the elements in the firstgear set 301 to rotate at unity and since gear set 301 is rotating 1:1then because ring R301 is connected to carrier C302 and sun S301 isconnected to sun S302, then carrier C302 is also rotating at 1:1.Carrier C303 will also rotate at 1:1 because ring R302 is connected tocarrier C303 and carrier C302 is connected to sun S303. This conditiongenerates a third condition of speed and torque.

Although particular preferred embodiments of the invention have beendisclosed in detail for illustrative purposes, it will be recognizedthat variations or modifications of the disclosed apparatus, includingthe rearrangement of parts, lie within the scope of the presentinvention.

What is claimed:
 1. An electric axle assembly comprising: a motor housing unit having motor housing chambers which are open on at least one side; a pair of electric motors arranged end-to-end within said motor housing chambers respectively and having a cooling manifold plate disposed between inboard ends of said motors, said electric motors being fixedly secured in position on opposite sides of the cooling manifold plate to axially align the electric motors, and wherein the cooling manifold plate encloses said electric motors within said respective motor housing chambers; wherein each of said motors includes a motor end plate, which is provided in said open side of each of said motor housing chambers, said manifold plate being disposed between said motor end plates axial alignment therewith, wherein said motor end plates and said manifold plate include complementary alignment formations which align a shaft axis of each said motor with a shaft axis of the other said motor and wherein each of said motor end plates is aligned with said manifold plate by a hub which projects from one of said motor end plate and said manifold plate and is received in a complementary socket in the other of said motor end plate and said manifold plate.
 2. The electric axle assembly according to claim 1, wherein said motor housing unit comprises first and second motor housings which each define a respective one of said motor housing chambers, said manifold plate being sandwiched between inboard ends of said motor housings.
 3. The electric axle assembly according to claim 2, wherein said manifold plate is compressed between said motor housings by fasteners extending therebetween.
 4. The electric axle assembly according to claim 2, wherein each of said motors includes a respective output shaft which is rotatable about a shaft axis to drive a vehicle wheel, said manifold plate being fixed to each of said first and second motor housings such that said output shafts and said shaft axes are aligned in registry with each other.
 5. The electric axle assembly according to claim 1, wherein said manifold plate is connected to a cooling system and has manifold passages routing coolant to and from said motors to effect cooling of said motors during operation.
 6. The electric axle assembly according to claim 5, wherein said manifold passages of said manifold plate comprise inlet and outlet cooling channels, said inlet cooling channel having an inlet port connected to said cooling system for receiving cooled coolant therefrom and communicating with first coolant ports of said motors to supply cooled coolant thereto, and said outlet cooling channel communicating with second coolant ports of said motors to receive heated coolant therefrom and having an outlet port connected to said cooling system for discharges said heated coolant.
 7. The electric axle assembly according to claim 6, wherein said manifold plate has opposite side faces disposed in close association with opposing motor faces of said motors, said inlet and outlet coolant channels being open through said side faces but closed by said motor faces.
 8. An electric axle assembly comprising: a motor housing unit having motor housing chambers which are open on at least one side, said motor housing unit comprising first and second motor housings which each define a respective one of said motor housing chambers; a pair of electric motors arranged end-to-end within said motor housing chambers respectively; and a cooling manifold plate disposed between and in contact with inboard ends of said first and second motor housings, said electric motors being fixedly secured in position on opposite sides of the cooling manifold plate, said manifold plate being connected to a cooling system and having manifold passages routing coolant to and from said motors to effect cooing of said motors during operation; wherein said manifold passages of said manifold plate comprise inlet and outlet cooling channels, said inlet cooling channel having an inlet port connected to said cooling system for receiving cooled coolant therefrom and having an outlet port connected to said cooling system for discharging said heated coolant, said inlet cooling channel is in fluid communication with first coolant ports of said motors to supply cooled coolant thereto, and said outlet cooling channel is in fluid communication with second coolant ports of said motors to receive heated coolant therefrom; and wherein said manifold plate has opposite side faces disposed in close association with opposing motor faces of said motors, said inlet and outlet coolant channels having open channel sides which open through said side faces but said channel sides being closed said motor faces.
 9. The electric axle assembly according to claim 8, wherein each of said inlet and outlet cooling channels extends face-wise along said side faces of said manifold plate to define a respective channel length.
 10. The electric axle assembly according to claim 9, wherein each of said first and second coolant ports projects axially from a respective said motor and being received axially into said respective one of said inlet and outlet cooling channels through said open channel sides.
 11. The electric axle assembly according to claim 10, wherein said first coolant ports are spaced along said respective channel length of said inlet cooling channel and said second coolant ports are spaced along said respective channel length of said outlet cooling channel.
 12. The electric axle assembly according to claim 8, wherein each of said motors includes a respective output shaft which is rotatable about a shaft axis to drive a vehicle wheel, said manifold plate and said motors having complementary recesses and projections which align said motors relative to said manifold plate such that said output shafts and said shaft axes of said motors are aligned in registry with each other.
 13. An electric axle assembly comprising: a motor housing unit having motor housing chambers which are open on at least one side, said motor housing unit comprising first and second motor housings which each define a respective one of said motor housing chambers; a pair of electric motors arranged end-to-end within said motor housing chambers respectively, each of said motors including a motor end plate, which is provided it said open side of each of said motor housing chambers; and a monolithic, one-piece cooling manifold disposed between inboard ends of said motors wherein said cooling manifold is sandwiched between said motor end plates, said cooling manifold being connected to a cooling system and having inlet and outlet cooling channels routing coolant to and from said motors to effect cooling of said motors during operation, said inlet cooling channel having an inlet port connected to said cooling system for receiving cooled coolant therefrom and communicating with first coolant ports of said motors to supply cooled coolant thereto, and said outlet cooling channel communicating with second coolant ports of said motors to receive heated coolant therefrom and having an outlet port connected to said cooling system for discharging said heated coolant thereto; said cooling manifold having opposite manifold side faces disposed in close association with opposing motor faces of said end plates, said inlet and outlet coolant channels being open through said manifold side faces but closed by said motors faces: wherein said inlet and outlet coolant channels have open channel sides which open through said manifold side faces of said cooling manifold plate toward said motor end plates and wherein each of said inlet and outlet cooling channels extends face-wise along said manifold side faces to define a respective channel length.
 14. The electric axle assembly according to claim 13, wherein said cooling manifold is compressed between said motor housings by fasteners extending therebetween.
 15. The electric axle assembly according to claim 13, wherein each of said first and second coolant ports projects axially respectively from a said motor end plate and being received axially into said respective one of said inlet and outlet cooling channels through said open channel sides.
 16. The electric axle assembly according to claim 15, wherein said first coolant ports are spaced along said respective channel length of said inlet cooling channel and said second coolant ports are spaced along said respective channel length of said outlet cooling channel.
 17. The electric axle assembly according in claim 13, wherein said cooling manifold is formed of a solid, plate-shaped body formed with said inlet and outlet cooling channels opening through said manifold side faces and said inlet and outlet ports extending in a face-wise direction from said inlet and outlet cooling channels and opening through an edge of said cooling manifold.
 18. The electric axle assembly according to claim 13, wherein one said inlet port and one said outlet port are provided which fluidly communicate with both of said motors for cooling thereof.
 19. The electric axle assembly according to claim 13, wherein one of said inlet port and said outlet port are connected to power electronics for cooling of said power electronics.
 20. The electric axle assembly according to claim 19, wherein said power electronics comprise at least one power inverter.
 21. The electric axle assembly according to claim 20, wherein said outlet port supplies said coolant to said power electronics. 